Kolor-Pikker
Member
No, it's just this lens, at least by what I know. The 55mm wouldn't be notorious for it's field curvature if it were a common trait among Pentax lenses. I rarely shoot images like the one above, so it's not a big problem. For "3D" subjects like this one it's even advantageous: https://dl.dropboxusercontent.com/u/41183616/_IMG2170.jpgI assisted a lot of fashion photographers and their preferred brand was Pentax. Despite being temperamental and often having shutter problems requiring as many as 2 back up bodies for a shoot (at least in the case of the Pentax 67) the lenses produced the most beautiful skin tones and bokeh. Is the field curvature of the 55mm a common trait of Pentax lenses and therefore an explanation for Pentax popularity amongst fashion photographers???
What I do find as a common trait is a high level of LoCA, that is magenta/green fringing of detail in front of or behind the plane of focus, all of the Pentax lenses I've used have it, even when stopped down a little. The 150mm is the worst offender (wide-open), but at f/8 it's also the sharpest lens I've ever used, with an absolutely flat field; because of this I use it for art reproduction whenever possible.